The detection and quantitative determination of hydrogen peroxide and of compounds yielding hydrogen peroxides such as glucose are of importance in many areas. Known compositions for detecting and/or quantifying hydrogen peroxide generally comprise a substance having peroxidative activity and a material which undergoes a detectable change (generally a color change) in the presence of hydrogen peroxide and the peroxidative substance.
It would be useful, and in some cases necessary, for a diabetic to maintain better quantitative control over blood glucose levels. One strategy contemplates providing diabetics with (1) a dry analytical element comprising a glucose test slide containing all of the reagents needed to determine glucose blood levels and (2) a small pocket reflectometer which uses a light emitting diode (LED) as a light source. This strategy faces several problems.
First, many of the prior art methods for detection of hydrogen peroxide are not useful in determining glucose. This is because glucose is present in relatively high levels in blood serum. Thus glucose generates large amounts of hydrogen peroxide. Correspondingly large amounts of dye are produced. The test elements usually become optically dense resulting in high reflection densities. An accurate reading of very dense test elements requires a good reflectometer. Such tests are not available for home use by diabetics because of the high cost of good reflectometers.
Secondly, commercially available light emitting diodes vary widely in their light intensity versus wavelength profiles. This variation could lead to considerable calibration difficulties.
Thirdly, hemoglobin interference up to 620 nanometers in some tests necessitates the use of a white rug or dye to mask the hemoglobin which further drives up test costs.
Thus in order to make available a reasonably accurate home testing kit for diabetics the above problems have to be overcome. More specifically, the problems are to provide a dye development composition that (1) does not develop too high a reflection density in the face of high levels of blood glucose and (2) develops a dye having a broad absorption band beyond 620 nanometers to allow reflection density readings beyond 620 nanometers thereby avoiding hemoglobin interference and overcoming problems of light emittent diode variation.